Evil Servo bypass
 

My 78 300SD has no heat. A few years ago it didn't have heat and i took it in and had the amplifier replaced. That fixed it and had heat. Last winter my heat stopped, there was clicking behind the glove box, intermittently the heat wouldn't work and I figured the amp was going again, but never got around to replacing it. I spent all winter with no heat and cold defrost.

it getting cold and I want to get a part time job delivering pizza so I need heat this winter. I replaced the amo with a known working one and no heat. All the buttons work and blow air (cold) so I guess it's the evil servo this time. Or could it be the thermostat?

If it's the thermo, I can replace that pretty easily, if it's servo, I cannot afford to replace it so it will be bypass time. I did a search and there are many many threads on it, but I want the best one and hopefully one that give my feet heat as well as hot defrost.

I know that every winter this comes up, so please have pity and patience with me.

Thanks and glad to see all the familiar names still here!

Ginny

Bypass is all of a $5 fix. PS cannot think of a worse pizza delivery car. Honda civic and the like were made for that role.

MB use a thermostatic cabin heat control that constantly samples cabin temp, this lives just "behind" the glove box....

If I had a beer for everyone who pulled a dash apart / duo valve / etc only to find it was the sensor I could float a battleship.

Is this the amp? I just replaced that to no avail.
If not what does the sensor look like? Photo?

Thanks!

So yall still got the Pizza shop up and flying?? :chef2:

bump for parts pix LOl

Temp Sensor for InBoard Ambient Air
 

on the 116.120 the location is inset into the forward most center dash point.

Hidden under the (By Now BRITTLE)

Little Square Plastic louvered grill just under the Windshield ,inset into the Dash.

Hey Jimmy! Nope, we turned the bar into a sit down pizza/ice cream place in April last year. We closed it July last year because of lack of funds. We were literally out of money everywhere! We used a mortgage payment to pay all the employees (and then went to family only working it) and the utilities and taxes for the month of june. I was working open to close 6 days per week, my 15yo daughter was working 60 hours and son was working 45 hours. My husband worked 12 hours on Sundays so I could catch up on sleep. We tried our best. We put every bit of money, sweat and time we could but it just didn't happen in time for us. If I had just had another $10K I could have ridden it out until shcool was back in, but I just couldn't find money anywhere.

So i am back in school, skating roller derby, and having nights with my family. We are al happier, healthier and I'm a straight A student. Sociology major.

But cold in my no-heat car!
:)

Great! Thanks for this, how do I know it would be this sensor?
All my buttons work and blow, just cold air. Would that happen if the temp sensor is dead? Would this also happen if the servo unit is not working? Would it happen if the thermostat in the coolant is dead?

Is this sensor easy to get or will I be looking high and low for the part?

Thanks! :):)

just a bump. . .:D

need a little more info before I start this project.

Here is a manual from the Imperial Club, orginally posted by KERRY.

http://www.imperialclub.com/Repair/Lit/Master/281/index.htm

Info on the servo

Charlie